Protective circuit for gaseous conduction tubing



July 17, 1951 L. H. LAMONT 2,560,771

v PROTECTIVE CIRCUIT FOR GASEOUS CONDUCTION TUBING Filed April ll 1949 I INVENTOR.

ATTY.

Lamb's HLWRZ Patented July 17 1951 .1

' l worriso e, omourr FOR GASEOUS CONDUCTION TUBING I Lewis H. Lamonhchicago, Ill.

1 ,Application pril 11, 1949, Serial No. 86,731

" 2'-Claims.

My present invention relates to protective circuits for gaseous conduction tubing.

It is the principal purpose of the present invention to provide a simple effective circuit which can be used with the transformer that supplies current to the tubing so that the primary circuit of the transformer will be opened in case the tube circuit is opened by a burned out tube or is grounded. My invention contemplates the combination with the transformer and tube of a relay and a mid-point ground connection for the tubing so that the relay will operate to open the primary circuit and will lock itself energized in so doing, thus making it necessary to break the supply of current to the relay before the transformer can again be energized.

The nature and advantages of my invention will appear more fully from the following description and the accompanying drawing illustrating a preferred form of the invention. It should be understood however, that the description and drawing are illustrative only and are not intended to limit the invention except as it is limited by the claims.

The drawing illustrates schematically the tube, the transformer and the circuit by which the control relay is associated therewith.

The tubing is illustrated in the drawing as cornprising a plurality of tubes I and 2. It is customary in lighting these gaseous conduction tubes to use a plurality of tubes in connection with one transformer. The transformer is indicated at 3 and has a primary winding 4 and a secondary winding 5. The secondary winding has its terminals connected by leads 6 and 1 across the tubing I-2. The primary winding 4 is energized from a suitable source of alternating current by a grounded lead 8 and a return lead 9 which is connected to the source of current through normally closed contacts II] of a relay II and a switch l2.

The tubing I-2 has a mid-point ground connection l3 which is preferably made through a spark gap I4. With the spark gap M in circuit it is not necessary to be very accurate in the placing of the mid-point connection to the tubing. However, the difference in the length of the tub- I ing on opposite sides of the connection I3 should not be over one foot in cases where the total length of the tubing across the transformer is small.

The transformer 3 is insulated from ground and normally placed in a separate metal housing for safety and the separate metal housing is grounded to comply with the national electrical code that transformers must be grounded. A mid-point lead I5 is brought up from the secondary winding 5 of the transformer 3. The lead I5 is connected to the relay II by a lead Hi, the other side of the relay II being connected by a lead I! to the lead 9 between the switch l2 and the normally closed contacts ID. The lead I5 is connected through normally open contacts l8 of the relay I I and a lead I9 to the grounded lead 8.

In operation the relay ll, of course, does not interfere with the supply of current of the primary winding 4 of the transformer 3. Any time the manual switch I2 is closed, current is supplied to the winding 4. Now, if one of the tubes l2 is broken there is immediately an increasing potential across the secondary winding 5 of the transformer which will cause current to flow across the ground gap I4 and this in turn draws current through the relay II to energize the relay. When the relay l is energized it opens the normally closed contacts II] to interrupt the circuit of the primary winding 4. At the same time the normally open contacts I8 are closed to establish a circuit from the alternating current source through the winding of the relay ll over the leads IT, IS and I9. The relay will remain energized until the switch I2 is opened and will keep the circuit of the primary winding 4 open at the contacts II). If either of the leads 6 or I become grounded current will also flow through the winding of the relay I I over the lead I5 to energize the relay and effect opening of the primary circuit. In the event tubing on both sides of the ground lead [3 is broken simultaneously the relay I I will not prevent high secondary voltage building up on the secondary winding 5, however, it is quite obvious that such a condition would rarely if ever, occur.

It is believed that the nature and advantages of my invention will be clear from the foregoing description. Having thus described my invention, I claim:

1. In a circuit for gaseous conduction tubing, the combination with the tubing of a transformer having a primary winding provided with leads for connection to a source of alternating current, a ground connection for one lead, said transformer having a secondary winding provided with terminals across which the tubing is connected, 2. ground connection from the mid point of said tubing, a relay, a mid point lead from the secondary winding of the transformer through the energizing winding of said relay to the ungrounded lead from the source of current to the primary winding, said relay having normally open contacts, operable when the relay is energized by flow of current through its coil to connect the mid point lead to the grounded primary lead to the source of current, said relay also having normally closed contacts in one of the leads from the primary winding to the source of current.

2. In a circuit for gaseous conduction tubing, the combination with the tubing of a transformer having a primary winding provided with leads for connection to a source of alternating current, a ground connection for one lead, said transformer having a secondary winding provided with terminals across which the tubing is connected, at ground connection from the mid point of said tubing, said last named ground connection including a spark gap, a relay, a mid point lead from the secondary winding of the transformer through the energizing winding of said relay to the ungrounded lead from the source of current.

to the primary winding, said relay having normally open contacts, operable when the relay is- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,294,623 Lebrun Sept. 1, 1942' 2,305,096 McDermott Dec. 15, 1942. 

